Canadian Forest Service Publications

Effects of overstory mortality on snow accumulation and ablation. 2008. Teti, P. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC. Mountain Pine Beetle Working Paper 2008-13. 34 p.

Year: 2008

Issued by: Pacific Forestry Centre

Catalog ID: 29047

Language: English

Series: Mountain Pine Beetle Working Paper (PFC - Victoria)

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Total annual runoff and peak streamflows from watersheds draining B.C.'s Interior Plateau are largely driven by spring snowmelt, which in turn is influenced by the condition of forests. Those forests are dominated by Lodgepole pine and are undergoing rapid change due to the mountain pine beetle epidemic. This project has documented physical stand characteristics, snow accumulation, and snow ablation rates of growing managed stands and deteriorating natural stands in six groups of plots.

Thirty-six long-term research plots were established in six groups in the Vanderhoof, Quesnel, Chilcotin, Central Cariboo, and Kamloops Forest Districts. Plot characteristics were documented by doing detailed tree and coarse woody debris surveys, and by taking fisheye canopy photos from which solar radiation transmittances and other optically-derived parameters were calculated. Snow accumulation and ablation rates were documented by ground surveys and aerial photography in 2006 and 2007.

In four of the six groups, where snow accumulation data are considered most reliable, snow water equivalents were highest in plots that had been clearcut or burned in a wildfire within the last 10 years. Snow accumulation was lowest in old foliated stands and managed stands greater than 25 years old. Accumulation in beetle-attacked stands relative to nearby cutblocks less than 10 years old ranged from 77% (Rosita) to 90% (Vanderhoof). Also in four of the six groups, snow ablation rates were highest in stands that had been logged less than 15 years earlier. Ablation rates in managed stands more than 30 years old were similar to those in old intact forests. These results suggest that logging dead pine stands will increase the total amount and rate of spring snowmelt over what would have otherwise occurred for about 15 years.